With one divorce under her stylish yet affordable belt, Jessica Simpson knows how tough it can be to keep relations friendly after a marital meltdown. But Life & Style claims she's trying to do just that with Pete Wentz in the wake of his split from her little sis, Ashlee.

Jess and her mom, Tina, were supposedly spied having a heart-to-heart with Pete about 2-year-old son Bronx during a recent rendezvous in the lobby of the Ritz-Carlton in New York.

"Tina talked about going to graduations together as a family for Bronx," says a spy, "and how they were going to make the future work post-divorce."

Wentz, who earlier this month assured Ryan Seacrest that he has "nothing but love and respect" for his estranged missus, despite a brewing custody tussle, allegedly told the Simpsons that he has "zero rage toward Ashlee."

That's … reassuring, we suppose.

Meanwhile, the tab accuses Mama Simpson of calling out her youngest daughter's apparent green-eyed streak after Wentz made his exit from the hotel.

"Ashlee is jealous of Pete being on tour," she is quoted as saying about the couple's breakup. "She wants to be onstage having her own success."

Meanwhile, in happier and less dubious Simpson relationship news, Jess says she plans to have a hand in creating the dress she'll wear when she becomes Mrs. Eric Johnson.

"I will be part of designing my own wedding gown," the onetime mom-jeans enthusiast and sometime fashion victim tells WWD. "No date has been set yet. We've both been married before. We're enjoying our commitment to each other. We want to take our time."